If you find yourself or a loved one frequently saying, “What did you say?” or “Speak up!” hearing loss might be the culprit. Research has shown that people with diabetes are twice as likely to experience hearing loss as those without diabetes, suggesting that it may be a complication of the disease.

“Physicians should refer patients with circulatory problems, no mattertheir age, to an audiologist,” she says. “I see people who are 85 or 90 years old, and they’ve never had a hearing screen. It’s important to have a baseline.”

The Listening Link

Although current research has drawn no firm conclusions about any association between diabetes and hearing problems, experts suspect there may be a relationship. Circulatory problems, such as those seen in heart disease, kidney disease, and diabetes, can affect the blood vessels in the ears. “It’s a very fine area with very fine blood vessels, and as the diabetes interferes with circulation, it interferes with hearing,” Enock says.

Kathleen Bainbridge, PhD, an epidemiologist at the National Institute on Deafness and Other Communication Disorders, says there are some theories about how diabetes may affect hearing. Bainbridge investigated hearing loss in people with diabetes in a 2008 study published in the Annals of Internal Medicine and found that people with diabetes are twice as likely to have hearing impairment as people without the disease, and those with prediabetes have a 30 percent higher rate of hearing loss, compared with people with normal blood glucose. While the study did not look at what was happening to the tissue in the inner ear, Bainbridge says that diabetes could be affecting the blood vessels.

“Hearing loss might be another complication of poorly managed diabetes or perhaps diabetes of long duration, much like diabetic kidney disease or diabetic retinopathy,” she says. “Like the kidneys, the structure of the inner ear is highly vascularized, so hearing loss might be the result of changes to the small blood vessels of the inner ear.”

Kathleen Yaremchuk, MD, chair of the Department of Otolaryngology–Head and Neck Surgery at Henry Ford Hospital in Detroit, says that similar to the microvascular damage observed in the eyes and kidneys of people with uncontrolled diabetes, a response may occur in the ears, too. “The better controlled,” she says, “the less likely you are to suffer the untoward consequences.”

Another theory is that diabetes could cause changes to the sensory neurons or fibers of the auditory nerve. The condition is already known to cause peripheral nerve damage in the feet and hands of people with uncontrolled diabetes, says Bainbridge.

Furthermore, because noise is a factor for hearing loss in general, Bainbridge says, “it’s possible that people with diabetes are particularly susceptible to the negative effects of sustained loud noise.” But she notes that none of these theories have been definitively explained by existing research.

Gender Studies

A 2012 study from Henry Ford Hospital found that women between the ages of 60 and 75 with uncontrolled diabetes had more hearing loss than women in that age group with well-controlled diabetes. Researchers also learned that hearing was worse overall in women younger than 60 with diabetes—even well-controlled diabetes—than in women without diabetes. Yaremchuk, the principal investigator for the study, says that while it’s impossible to speculate about what is happening in the ears without a microscopic evaluation, the study did show that diabetes is a risk factor for hearing loss.

For the study, Yaremchuk and her team looked at records for 990 patients who had audiograms, a type of hearing assessment, between 2000 and 2008 at the hospital. People with diabetes were put into two groups: those with well-controlled diabetes and those with uncontrolled diabetes, based on American Diabetes Association A1C targets. After evaluating participants’ ability to hear at certain frequencies and recognize speech, the researchers found that hearing loss was associated particularly with older women with uncontrolled diabetes and younger women with diabetes in general.

Men were found to have worse hearing overall compared with the women in the study, regardless of their age or whether they had diabetes. There was also no significant difference in hearing among men with uncontrolled diabetes, those with well-controlled diabetes, or those who did not have diabetes.

“We know what normal is for different age groups, and those patients with diabetes were found to have increased hearing loss that wouldn’t be expected for their age,” says Yaremchuk.

Bainbridge agrees that good diabetes control is important for overall health, but says that it’s hard to know for sure if this will prevent hearing loss, as it hasn’t been explicitly tested. “[Blood glucose management is] continued good practice for people with diabetes, and they may have the benefits of a lesser degree of hearing loss,” she says, “but it hasn’t yet been borne out in the research.”

Risk Factors

Another study, published in 2011 in Diabetes Care, looked at risk factors for hearing loss in people with diabetes and found that low HDL (“good”) cholesterol, coronary artery disease, peripheral neuropathy (nerve damage), and poor health in general increased the risk for hearing loss. Researchers stated that those factors are potentially preventable, however, and could reduce the risk for hearing loss if controlled.

Among people with diabetes, those who were older, white, male, or had a lower income had a greater likelihood of hearing impairment. In addition, they found that blood glucose control, years since diagnosis, and type of diabetes medication did not seem related to hearing loss.

Bainbridge says that while she has looked at A1C levels in people with diabetes and did not find a connection with hearing loss, a recent Japanese study found that elevated A1C levels were correlated with an increased risk for hearing loss in the future. “That’s starting to show early evidence that [hearing loss] might be related to blood glucose levels,” she says.

Hearing Aid

While it may be possible to prevent hearing loss by controlling diabetes and other health problems, what about people who are already hard of hearing? For that, Enock says hearing aids help.

“The beauty of the digital hearing age is we can now shape the sound,” she says. In the past, all hearing aids were analog and amplified all sounds, but digital hearing aids are much nimbler. If background noise is too loud, digital hearing aids can filter it out.

Enock says hearing aids may be able to help keep the brain connected to the world—and people with hearing loss connected to life. It is very important, says Enock, to ensure that the brain continues to be stimulated by hearing and understanding words. “If we don’t get the signal to the brain, the brain loses the ability to understand,” she says. “The ears are just a conduit to the brain. The brain is doing all the thinking.” For example, consonants are in a much higher frequency range than vowels, and add clarity to speech. So high-pitched hearing loss can make it difficult for the brain to understand words and their meaning, she adds.

In fact, hearing loss and dementia may be linked, according to a 2011 study from Johns Hopkins University. Researchers found that people with mild hearing loss were twice as likely to develop dementia as those with perfect hearing. The risk of dementia was three times greater in participants with moderate hearing loss and five times greater in those with severe hearing loss.

Enock and Yaremchuk agree that if you notice yourself or a family member having trouble hearing or understanding, it’s essential to be screened for any problems.

Signs of Hearing Loss

The following behaviors can indicate hearing loss, according to Debbie Abel, AuD, a senior specialist at the American Academy of Audiology:

In Others

They frequently ask you to repeat yourself.

They seem to have difficulty hearing when there’s background noise, such as at a restaurant.